Annstown was a region in the north corner of the Seigniory of Beauharnois. It was bounded on the northeast by the Seigniory of Châteauguay, on the northwest by the St-Lawrence River and the lower part of the St-Louis River, on the southwest by the region of North Georgetown (border line was the Rang St-Laurent) and on the southeast by the Châteauguay River. It included parts of the parishes of St-Clement (Beauharnois), Ste-Martine and St-Ètienne de Beauharnois.